Sensitive high capacity room thermostat

ABSTRACT

The invention comprises a plastic face plate which senses ambient temperature and operates a metal amplifier plate which bows outwardly of the face plate to actuate a thermostat switch. The differential expansion of the two plates causes the switch actuation.

United 3 States Patent Beck I 3,663,916 [451 May 16,1972

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[21] Appl. No.: 749,715

Primary Examiner-Bernard A. Gilhean Assistant Examiner-Dewitt M. Morgan 8, 337/380 Attorney-C. Cornell Remsen, Jr., Walter J. Baum, Paul W. HOlh 37/46 Hemminger, Percy P. Lantzy and A. Donald Stolzy .337/123, 126, 139, 382, 384, 3 337/386, 388, 389, 3 [5 [52] US. Cl................................337/396, 337/36 [5 1] Int. Cl....,...........H0lh 37/12, HOlh 37/22,

ABSTRACT prises a plastic face plate which senses am- [58] FieldoiSearch.................

92, 393, 398, 400, 390, 391, 396, 135, 3l9, 347, 368, 300; 200/166 M, 67 D The invention com bient temperature and operates a metal amplifier plate which plate to actuate a thermostat pansion of the two plates causes the bows outwardly of the face switch. The differential ex switch actuation.

UNITED STATES PATENTS 3,423,713 Levinn.................... 337/368 X 2,848,569 Moss et al. 66 M 5 Claims, 4 Drawing Figures PATENTEDMAY 16 I972 3.663 .9 1 6 sum 1 or 2 INVENTOR Edd/W0 0 566K A TTGEA/EV BY '4 l/ 'PATENTEDMAHBIHYZ 3.563.916

SHEET 2 [IF 2 INVENTOR Edd/W00. 566K 1 SENSITIVE HIGH CAPACITY ROOM THEglMOSTAT BACKGROUND OF THE INVENTION The invention relates to heat sensing devices, and more particularly to an improved inexpensive thermostat.

In detecting the temperature of a room, a bimetal strip is conventionally employed which is notexposed directly to the air for appearances sake. In the past, efforts have been made to overcome the use of a bimetal in a thermostat. Such is shown in US. Pat. No. 2,649,523. However, the past efforts have been rather complicated and expensive, and have what is known as fdroop". Droop occurs when heat is generated in the thermostat switch. This, in turn, heats the temperature sensing .device and turns off the furnace before the room actually gets up to temperature.

SUMMARY OF THE INVENTION In accordance with the device of the present invention, the above-described and other disadvantages of the prior are are overcome by providing athermostat control including a face plate, and an amplifier plate having its ends fixedrelative to the end of the face plate. The differential expansion of the two plates causes switch actuation. Due to the fact that the face plate is open to the atmosphere, the droop problem of the prior art is overcome. Further, the face plate has grooves into which the amplifier plate snap fits. The thermostat control of the invention is therefore a relatively control.

The foregoing and other advantages of the present invention will be better understood from the following description when consideration in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, which are to be regarded as merely illustrative, t

FIG. 1 is a perspective view of one embodiment of the present invention; 7

FIG. 2 is a sectional view taken on the line 2-2 shown in FIG. I; Y

FIG. 3 is a perspective view of an amplifier plate employed with the invention; v I FIG. 4 is a front elevational view, partly in section, showing the dial of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT simple and inexpensive switch. Switch 18 may thus be entirely conventional.

17 has a projection 21 which fits behind'a flange 22-on base l3. A screw 23 holds a portion 24 of bracket 17. The screw 23 is threaded through a projection 25 integral with base 13.

Face plate 11 is fixed to bracket 17 by eyelets 26 and 27.

Face plate 11 has grooves at 28 and 29 into which the ends of an amplifier plate 30 are snap fit. .Amplifier plate 30 is bowed to the right as shown in FIG. 2. t

The construction of amplifier plate 30 is better illustrated in FIG. 3. Amplifier plate 30 has an opening 31 through which eyelet 26 projects to fix face plate 11 to bracket 17. Amplifier plate 30 also has an opening 32 through which eyelet 27 projects to fix face plate 11 to bracket 17. Amplifier plate 30 has a serrated opening 33 to which a bushing 34 is staked as shown in FIG. 2.

Bushing 34 is threaded internally. Dial 12 has a projection As shown in FIG. 1, dial 12 has indicia at 37. This indicia is compared with a projection 38 that is integral with face plate 1 1. When the temperature of indicia 37 is matched to the position of projection 38, switch 18 will be actuated at a corresponding temperature.

Set screw 36 is provided to calibrate the instrument. When amplifier plate 30 bows out sufiiciently from face plate 11, set screw 36 will depress a button 39 on switch 18 and actuate the In the operation of the thermostat control of the present invention, set screw 36 is adjusted to calibrate the control. Dial 12 is then turned to a desired temperature. This will locate screw 36 at a pre-detennined position relative to switch 18. .Face plate 1 1' may be made of a conventional plasticsuch as a polycarbonate plastic, Amplifier plate 30 may be made of stainless steel. Amplifier plate 30 will thus bow out more or less dependent upon the temperature. The difi'erential expansion of faceplate l1 and amplifier plate 30 will thus cause actuation and deactuation of switch 18.

From the foregoing, it will be appreciated that face plate 1 l is always in open and direct contact with the air surrounding the same. The droop problem of the prior art is therefore solved. Further, the simple snap fit construction of plates I1 and 30, make the thermostat control of the present invention simple to construct and inexpensive to manufacture.

Many changes and modifications of the invention will suggest themselves to those skilled in the art. The invention is therefore, not to be limited to the specific construction selected for' this disclosure, the true scope of the invention being defined only in the appended claims.

What is claimed is:

l. A thermostat comprising: a substantially flat face plate; an amplifier plate having its ends fixed relative to the ends of said face plate in a position to bow outwardly of the face plate on one side thereof, said face plate having a higher thermal coefiicient of expansion than that of said amplifier plate; a base adapted to be located in a fixed position; a switch fixed to said base, said switch having an actuating member positioned at the center of said amplifier plate; means fixed to the center of said amplifier plate to move said member when said amplifier plate moves, said amplifier plate having a hole therethrough contiguous to the center thereof; and a rigid body fixed rigidly to said face plate and said base, said body holding the center of said face plate in fixed position, said body extending through saId amplifier plate hole spaced from and out of contact with saidamplifier plate, said amplifier plate being positioned between said face plate and said base.

2. Theinvention asdefined in claim I, wherein said face plate is made of plastic.

3. The invention as defined in claim 2, wherein said amplifier plate is made of metal.

4. A thermostat control comprising: a face plate; an amplifier plate having its ends fixed relative to the ends of said face plate in a position to bow outwardly of the face plate when said face plate cools, said face plate having a thermal coefficient of expansion substantially greater than that of said amplifier plate; a base; a switch having an actuating member; means to support said face plate near its center in a positionfixed relative to said base; means to support said switch in a position fixed relative to said base near the center of said amplifier plate; and adjustable means fixed to the center of said amplifier plate in a position such that said adjustable means engages said member at a predetermined temperature, said adjustable means including a bushing fixed to said amplifier plate, said bushing being internally threaded, a hollow shaft plifier plate, said plates being rectangular, said face plate being made of plastic, said amplifier plate being made of metal, said face plate having a groove at each end thereof to receive the corresponding ends of said amplifier plate, said amplifier plate having a length greater than the space between said grooves so as to snap fit therein and bow outwardly of said face plate; a base; a switch having an actuating member; means to support said face plate near its center in a position fixed relative to said base; means to support said switch in a position fixed relative to said base near the center of said amthreaded into said bushing, a control knob fixed relative to said shaft, and a set screw threaded inside said shaft in a position to engage said switch actuating member. 

1. A thermostat comprising: a substantially flat face plate; an amplifier plate having its ends fixed relative to the ends of said face plate in a position to bow outwardly of the face plate on one side thereof, said face plate having a higher thermal coefficient of expansion than that of said amplifier plate; a base adapted to be located in a fixed position; a switch fixed to said base, said switch having an actuating member positioned at the center of said amplifier plate; means fixed to the center of said amplifier plate to move said member when said amplifier plate moves, said amplifier plate having a hole therethrough contiguous to the center thereof; and a rigid body fixed rigidly to said face plate and said base, said body holding the center of said face plate in fixed position, said body extending through saId amplifier plate hole spaced from and out of contact with said amplifier plate, said amplifier plate being positioned between said face plate and said base.
 2. The invention as defined in claim 1, wherein said face plate is made of plastic.
 3. The invention as defined in claim 2, wherein said amplifier plate is made of metal.
 4. A thermostat control comprising: a face plate; an amplifier plate having its ends fixed relative to the ends of said face plate in a position to bow outwardly of the face plate when said face plate cools, said face plaTe having a thermal coefficient of expansion substantially greater than that of said amplifier plate; a base; a switch having an actuating member; means to support said face plate near its center in a position fixed relative to said base; means to support said switch in a position fixed relative to said base near the center of said amplifier plate; and adjustable means fixed to the center of said amplifier plate in a position such that said adjustable means engages said member at a predetermined temperature, said adjustable means including a bushing fixed to said amplifier plate, said bushing being internally threaded, a hollow shaft threaded into said bushing, a control knob fixed relative to said shaft, and a set screw threaded inside said shaft in a position to engage said switch actuating member.
 5. A thermostat control comprising: a face plate; an amplifier plate having its ends fixed relative to the ends of said face plate in a position to bow outwardly of the face plate when said face plate cools, said face plate having a thermal coefficient of expansion substantially greater than that of said amplifier plate, said plates being rectangular, said face plate being made of plastic, said amplifier plate being made of metal, said face plate having a groove at each end thereof to receive the corresponding ends of said amplifier plate, said amplifier plate having a length greater than the space between said grooves so as to snap fit therein and bow outwardly of said face plate; a base; a switch having an actuating member; means to support said face plate near its center in a position fixed relative to said base; means to support said switch in a position fixed relative to said base near the center of said amplifier plate; and adjustable means fixed to the center of said amplifier plate in a position such that said adjustable means engages said member at a predetermined temperature, said adjustable means including a bushing fixed to said amplifier plate, said bushing being internally threaded, a hollow shaft threaded into said bushing, a control knob fixed relative to said shaft, and a set screw threaded inside said shaft in a position to engage said switch actuating member. 